Vehicles typically employ conventional on/off brake lights that are triggered by application of a brake pedal to indicate that the vehicle's brakes are applied. Some vehicles are equipped with sequentially illuminating lamps visible to a trailing driver. The sequentially illuminating lamps may be illuminated upon decreasing vehicle velocity that is measured from a wheel speed sensor. Others of such systems may base deceleration on vehicle speed determined from a sensor attached to a brake pedal. Still other vehicles equipped with sequentially illuminating lamps may base vehicle deceleration upon measurements from a decelerometer.